Ripple detection device and seat device

Abstract

Ripple detection device and seat device are provided that can optimally control variable filter passband in accordance with motor driving state by using linear relational expression for deriving ripple current frequency based on ripple current and motor terminal-to-terminal voltage, and can detect ripple pulses with high accuracy. Ripple detection device includes ripple current detector for detecting ripple current generated when motor is driven, motor voltage detector for detecting motor terminal-to-terminal voltage, variable filter for passing a component, of the ripple current detected by ripple current detector, that is in predetermined frequency band, and frequency adjuster for adjusting predetermined frequency band of variable filter to include ripple current frequency derived using linear relational expression for deriving ripple current frequency based on ripple current detected by ripple current detector and motor terminal-to-terminal voltage detected by motor voltage detector.

What is claimed is: 
     
         1 . A ripple detection device, comprising:
 a ripple current detector configured to detect a ripple current generated when a motor is driven;   a motor voltage detector configured to detect a terminal-to-terminal voltage of the motor;   a variable filter configured to pass a component of the ripple current detected by the ripple current detector, the component being in a predetermined frequency band; and   a frequency adjuster configured to adjust the predetermined frequency band of the variable filter so as to include a frequency of the ripple current derived by using a linear relational expression for deriving the frequency of the ripple current based on the ripple current detected by the ripple current detector and the terminal-to-terminal voltage detected by the motor voltage detector.   
     
     
         2 . The ripple detection device according to  claim 1 ,
 wherein the linear relational expression is represented by an equation (1) below,   
       
         
           
             
               
                 
                   
                     fr 
                     = 
                     
                       
                         α 
                         × 
                         Ir 
                       
                       + 
                       
                         β 
                         × 
                         Vm 
                       
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
         where Ir represents the ripple current, fr represents the frequency of the ripple current, α represents a ratio of a change of the frequency of the ripple current to a change of the ripple current, and β represents a ratio of the change of the frequency of the ripple current to a change of the terminal-to-terminal voltage. 
       
     
     
         3 . The ripple detection device according to  claim 1 , further comprising:
 a temperature sensor configured to detect an environmental temperature of the motor,   wherein the frequency adjuster adjusts the predetermined frequency band of the variable filter so as to include a frequency of the ripple current derived by using a linear relational expression between the ripple current detected by the ripple current detector, the terminal-to-terminal voltage detected by the motor voltage detector, and the environmental temperature detected by the temperature sensor,   wherein the linear relational expression is represented by an equation (2) below,   
       
         
           
             
               
                 
                   
                     fr 
                     = 
                     
                       
                         α 
                         × 
                         Ir 
                         × 
                         K 
                       
                       + 
                       
                         β 
                         × 
                         Vm 
                       
                     
                   
                 
                 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
         where Ir represents the ripple current, fr represents the frequency of the ripple current, α represents a ratio of a change of the frequency of the ripple current to a change of the ripple current, K represents a variable temperature coefficient represented by an equation (3) below, and β represents a ratio of the change of the frequency of the ripple current to a change of the terminal-to-terminal voltage, 
       
       
         
           
             
               
                 
                   
                     K 
                     = 
                     
                       1 
                       - 
                       
                         γ 
                         × 
                         T 
                       
                     
                   
                 
                 
                   
                     ( 
                     3 
                     ) 
                   
                 
               
             
           
         
         where in the equation (3), γ represents a predetermined temperature coefficient, and T represents a temperature obtained by subtracting a predetermined reference temperature from the environmental temperature of the motor detected by the temperature sensor. 
       
     
     
         4 . The ripple detection device according to  claim 2 , further comprising:
 a memory configured to store data representing the linear relational expression represented by the equation (1).   
     
     
         5 . The ripple detection device according to  claim 3 , further comprising:
 a memory configured to store data representing the linear relational expression represented by the equation (2) and data representing the equation (3).   
     
     
         6 . The ripple detection device according to  claim 2 , further comprising:
 a ripple pulse generator configured to generate a ripple pulse from a signal output from the variable filter.   
     
     
         7 . The ripple detection device according to  claim 6 , further comprising:
 a first filter provided on an input side of the variable filter; and   a second filter provided on an output side of the variable filter,   wherein the ripple current that is detected by the ripple current detector and is passed through the first filter, the variable filter, and the second filter in this order is input into the ripple pulse generator.   
     
     
         8 . A seat device, comprising:
 a seat mounted on a vehicle, a position or an angle of the seat being adjustable by a motor;   a drive controller configured to control drive of the motor; and   a ripple detection device configured to detect a ripple current of the motor and output the ripple current to the drive controller,   wherein the ripple detection device includes:   a ripple current detector configured to detect the ripple current generated when the motor is driven;   a motor voltage detector configured to detect a terminal-to-terminal voltage of the motor;   a variable filter configured to pass a component of the ripple current detected by the ripple current detector, the component being in a predetermined frequency band; and   a frequency adjuster configured to adjust the predetermined frequency band of the variable filter so as to include a frequency of the ripple current derived by using a linear relational expression for deriving the frequency of the ripple current based on the ripple current detected by the ripple current detector and the terminal-to-terminal voltage detected by the motor voltage detector.